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<DIV><SPAN class=375551821-10082005><FONT face=Arial color=#0000ff size=2>Hi
Nat,</FONT></SPAN></DIV>
<DIV><SPAN class=375551821-10082005><FONT face=Arial color=#0000ff size=2>Just a
further complication, that if I remember the original E-mail, may be
useful.</FONT></SPAN></DIV>
<DIV><SPAN class=375551821-10082005><FONT face=Arial color=#0000ff size=2>If
your plane pitches to the belly AND rolls adverse with rudder, or pitches to the
canopy AND rolls proverse, then it is possible and likely that you have
only one problem, and not two. If you fix the pitching, then the roll may be
reduced, or if you stop the roll, the pitching may be reduced. In general, if a
rudder to aileron couple fixes things, you will have less interesting behavior
with rudder corrections in looping maneuvers. This is because most designs have
an angle-of-attack sensitive yaw-to-roll couple. That knowledge can save your
plane if you ever take off with the ailerons disconnected: slow down, get the
nose up, and turn with the rudder. At high AOA, the plane will roll like a high
wing trainer (well sorta!)</FONT></SPAN></DIV>
<DIV><SPAN class=375551821-10082005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=375551821-10082005><FONT face=Arial color=#0000ff
size=2>Regards,</FONT></SPAN></DIV>
<DIV><SPAN class=375551821-10082005> <FONT face=Arial
color=#0000ff size=2>Dean</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org]<B>On Behalf Of </B>Nat
Penton<BR><B>Sent:</B> Wednesday, August 10, 2005 5:00 PM<BR><B>To:</B>
discussion@nsrca.org<BR><B>Subject:</B> Re: more on the cause of "adverse roll
couple"<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Patrick, the roll axis must be parallel to the
wing zero lift line and pass thru or near the vert cg for the aerobatic
airplane. All moments about the roll axis must total zero when in
yaw.</FONT></DIV>
<DIV><FONT face=Arial size=2>Moment generators can be:</FONT></DIV>
<DIV><FONT face=Arial size=2>
1. Dihedral </FONT></DIV>
<DIV><FONT face=Arial size=2>
2. CLA vs vert cg</FONT></DIV>
<DIV><FONT face=Arial size=2>
3. Rud/fin area distribution</FONT></DIV>
<DIV><FONT face=Arial size=2>and probably others I am
overlooking.
Nat</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=ppandelaers@pandora.be
href="mailto:ppandelaers@pandora.be">PPandelaers</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=geobet@gis.net
href="mailto:geobet@gis.net">geobet@gis.net</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=discussion@nsrca.org
href="mailto:Discussion@Nsrca.Org">Discussion@Nsrca.Org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, August 10, 2005 12:29
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> more on the cause of "adverse
roll couple"</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hi Georgie, </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Would you mind giving your view
on the source of roll effect in the first place (without dihedral applied to
fix it)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">From the theory books I
read, here’s what I understand:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I think what you call datum line
is the following:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">- if on the fuselage. the
center of lateral area (CLA) and the vertical CG are connected, you get the
line which should be the wind-direction during flight as the plane faces it.
This is in fact the theoretical datum line, in most construction drawings
this line will be shifted up, but parallel with what I describe. So during
the design of a plane, you assume a desired flight attitude of the fuselage,
in this attidude youmake sure the CLA is on the height of the vertical
CG.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">- If the CLA <B><SPAN
style="FONT-WEIGHT: bold">is</SPAN></B> on this theoretical datum line
during knife edge ( and I tend to set wing incidence, hence fuselage
attidude, to fly knife edge as neutral as possible), assuming no
dihedral, than the only possible contributors to roll are:</SPAN></FONT></P>
<UL type=disc>
<LI class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Motor-side
thrust.</SPAN></FONT>
<LI class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Center of lateral area of
rudder, which should also be on this theoretical datum line</SPAN></FONT>
</LI></UL>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Don’t forget. The wing isn’t
flying.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Clearly, I must be overlooking
something serious, such that we need to apply dihedral to fix it. Can you
help?</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks!!</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Patrick</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN lang=EN-GB
style="FONT-SIZE: 12pt">What you're experiencing is known as "adverse roll
couple"! You can prove this just by flying right side up and applying full
rudder deflection in either direction and you will see that the airplane
will roll in the opposite direction to whatever rudder you are applying.The
cause of the phenomenon is that the wing is located too far below the Datum
line without sufficient dihedral to compensate for the
offset</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN lang=EN-GB
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P></DIV>
<P>
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